Twenty-four-hour measurement of IOP in rabbits using rebound tonometer

Abstract

Purpose: To observe the Intraocular pressure (IOP) measurements over a 24-h period in New Zealand white rabbits.

Methods: Thirty-four normal New Zealand white rabbits (68 eyes) were included in this study. The IOP values were determined with a rebound tonometer (RBT, Icare VET). Measurements were always obtained in the right eye first.

Results: The data showed that there was no significant difference in IOP between measurements, which indicated that the RBT showed good repeatability in this study (P = 0.920). There was no statistically significant difference between genders (P = 0.943). The IOP in right eyes was a little higher than left eyes (F = 45.96, P < 0.001). Comparison of the true IOP and RBT results over the entire pressure range (8-100 mmHg) revealed a statistically significant difference between them (P < 0.001). The mean difference between the RBT and true IOP (RBT-True IOP) was -22.65 ± 9.52 mmHg with 95% confidence interval (-27.1, -18.2 mmHg). In the light period (7 AM to 7 PM), the IOP was a little lower than during the dark period (8 PM to 6 AM); 9 AM and 2 PM were the lowest measurements (10 mmHg, 9.625 mmHg), and 10 AM (14.125 mmHg)was the highest measurement during the 24-h period.

Conclusions: The IOP obtained by RBT underestimated the true IOP but the RBT had a good repeatability in IOP measurements. In the light period (7 AM to 7 PM), the IOP was a little lower than during the dark period (8 PM to 6 AM), which may be beneficial to the intervention therapy observation of glaucoma research in rabbits.

Keywords: 24-h; intraocular pressure; rabbits; rebound tonometer.